cmake: disable GCC's format-truncation warning
cmake: disable GCC's format-truncation warning

GCC 8 warns about potential truncations when using formatted output using
heuristics to estimate the output length.

Such truncation is actually intended for ptdump to ensure a table-like
output.  Further, the heuristics may lead to false positives, which would
result in errors in our case.

Disable the warning by supplying -Wno-format-truncation.

Change-Id: Iad96772a896198ef3347be773838312f1c557806
Signed-off-by: Markus Metzger <5f675b2b36595f90898e014b548ff7d9bbff2ab7@intel.com>

01org/processor-trace,01org/processor-trace,01org/processor-trace